The present invention relates, in general, to rather commonly used high voltage test equipment and, more particularly, the invention relates to an apparatus for automated testing of individual wires or networked circuits. Still more specifically, this invention relates to an automatic high potential megohmeter and continuity circuit tester.
It will be appreciated that, in railway and mass and/or rapid transit operations, it is common practice to perform high potential (hi-pot) testing on individual wires as well as on networked circuits.
Applying a voltage of a predetermined magnitude between two points that are electrically isolated from each other in order to determine that minimum standards of the quality of electrical isolation between those points exist is commonly known as a hi-pot test. The hi-pot test typically involve applying a high voltage, for example 1500 volts, across two points of an isolated wire for a predetermined minimum amount of time. Any arc appearing between these two points indicates defective isolation in the wire. If no arc appears within the predetermined minimum voltage applied time, the isolation is deemed to be functioning correctly.
The nature of hi-pot testing demands that the high voltage be applied between the isolated points for at least a predetermined time period. This insures adequate stressing of the insulating material, used for providing isolation, by the applied high voltage in order to cause a break down of weak insulation, damaged wires, or wires that may have been installed improperly during an assembly process, which indicate a breakdown in isolation. Arcing within the insulation, which is used to provide proper isolation, indicates such breakdown. If the high voltage is applied for less than the predetermined amount of time, it is possible that a defective isolation will not have time to breakdown; therefore, it will appear to the testing apparatus that the test results are normal even though such defective isolation may exist.
High voltage test apparatus detect defects in electrical isolation by sensing an increase in current through a faulty isolated wire by causing the arcing. This increase in current will cause the test apparatus to sound an alarm, or in the case of an automatic test apparatus, to activate a reject test cycle.
In one aspect the present invention provides an apparatus used to perform an automatic high potential (hi-pot), megohmeter and continuity, circuit test. The apparatus comprises a power source connected to a central processing unit (cpu), a hi-pot means, and a power supply means. The cpu contains a floppy drive, a hard drive, an analog to digital (A/D) printed circuit board, and a predetermined number of digital I/O printed circuit boards. There is a data entry means connected to the cpu for providing input into the cpu. Displaying predetermined data from the cpu is provided by a visual display means. Also included is a hi-pot means connected to the A/D printed circuit board and to at least one of the predetermined number of digital I/O printed circuit boards, contained in the cpu, for providing a predetermined voltage of a predetermined magnitude. The apparatus further includes a multiplexer means connected to the power supply and to at least one of the predetermined number of digital I/O printed circuit boards and the hi-pot means for receiving a predetermined voltage of a predetermined magnitude and for communicating a predetermined quantity of signals indicative of a predetermined voltage of a predetermined magnitude. Finally it includes a predetermined number of external circuits connected to the multiplexer means for providing two-way communication of a predetermined quantity of signals.
In another aspect the present invention provides a method used to perform an automatic high potential (hi-pot), megohmeter and continuity, circuit test. The method comprises the steps of energizing a cpu, a hi-pot means, and a power supply means. Test parameters are determined and entered into the cpu. Generating in the cpu a digital control signal indicative of the test parameters and communicating the digital control signal to a hi-pot means. The hi-pot means generates an analog signal indicative of the digital control signal and communicates it to the A/D printed circuit board. The cpu verifies the analog signal and then utilizes the A/D printed circuit board to generate a digital signal. A high voltage signal is generated in the hi-pot means and is communicated it to a multiplexer means. The multiplexer utilizes the high voltage signal to perform a predetermined test on an external circuit. Upon completion of the predetermined test the multiplexer generates a predetermined test result signal indicative of the predetermined test, and communicates the predetermined test result signal to a predetermined digital I/O printed circuit board. The predetermined digital I/O printed circuit board generates a display signal upon receipt of the predetermined test result signal and communicates the display signal to a visual display means for visually displaying test results.
It is, therefore, one of the primary objects of the present invention to provide an automatic hi-pot, megohmeter and continuity, circuit tester that assures product quality.
It is also an object of the present invention to provide an automatic hi-pot, megohmeter and continuity, tester that improves reliability through the elimination of operator error.
An additional object of the present invention is to provide an automatic hi-pot, megohmeter and continuity, circuit tester that greatly reduces test times while improving accuracy.
Another object of the present invention is to provide an automatic hi-pot, megohmeter and continuity, circuit tester that provides a higher level of safety for workers.
These and various other objects and advantages of this invention will become apparent after a full reading of the following detailed description, particularly, when read in conjunction with the attached drawings as described below and the appended claims.